JPH10306857A - Hydraulic tensioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulic tensioner to minimize an air amount in a chamber and improve performance. SOLUTION: A hydraulic tensioner comprises a housing 102 having a hole 104; a hollow piston 130 slidably contained in a hole 104; a piston spring 170 to energize the piston 130 in a protrusion direction; and a valve housing having a hollow structure containing an inner chamber 313 and a plurality of valve housing apertures 216 and 311. The valve housing aperture 216 intercouples the inside chamber 313 and a pressure chamber 180, and the valve housing aperture 311 intercouples the inside chamber 313 and a pressure fluid source.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic tensioner, and more particularly to a hydraulic tensioner with an integrated suction check and relief valve having both functions of a suction check valve and a relief valve.

[0002]

BACKGROUND OF THE INVENTION its] should US patent application Ser. No. 08 / 516,919, entitled "inhalation relief valve for the tensioner for motor vehicles", which was filed on background August 18, 1995 of the invention is referred to is there. The subject of the application relates to the present invention.

[0003] A tensioning device such as a hydraulic tensioner is used as a control device for a power transmission chain or similar power transmission device traveling between a plurality of sprockets. In these devices, the chain transmits power from the drive shaft to the driven shaft, so that a part of the chain is loosened and another part is stretched. In the case of a toothed chain, it is generally important to provide and maintain a certain amount of tension in the chain to prevent noise, slippage or poor meshing.

The prevention of such slip is particularly important in the case of a camshaft driven by a chain in an internal combustion engine. This is because tooth skipping can shift the timing of the camshaft, damaging the engine or causing the engine to malfunction. On the other hand, in a severe environment in which an internal combustion engine is placed, various factors cause fluctuations in chain tension.

[0005] Wide variations in temperature and the coefficient of thermal expansion between the various parts of the engine change the tension of the chain between very high and very low values. During prolonged use, wear of components in the power transmission system reduces chain tension. Also, torsional vibrations caused by the camshaft and crankshaft significantly change chain tension. Reverse rotation of the engine, which occurs, for example, when the engine is stopped or when starting is poor, also changes the chain tension.

[0006] For this reason, a mechanism for removing the excessive tension on the tight side of the chain and securing the necessary tension on the slack side of the chain is desired. Hydraulic tensioners are a well-known means for maintaining proper chain tension. Generally, this mechanism employs a lever arm that exerts a pressing force on the chain on the slack side of the power transmission system. The lever arm must press against the chain when the chain is loose and exert tension on the chain, and must retract from the chain when the chain is stretched.

For this reason, a typical hydraulic tensioner has a rod or a cylinder as a plunger biased toward the chain by a tensioner spring. The plunger is housed in a cylindrical plunger housing. The housing has an open end facing the chain and a closed other end. The interior space of the plunger housing has a hydraulic chamber in communication with a reservoir or an external source of pressurized fluid. The hydraulic chamber is typically formed between the plunger housing and the plunger, and expands or contracts as the plunger moves within the plunger housing.

[0008] Two types of valves are commonly employed to regulate the flow rate into and out of the hydraulic chamber: an intake check valve and a relief valve.

[0009] The suction check valve typically includes a ball check valve that allows fluid to enter the chamber when the pressure in the chamber decreases due to the outward movement of the plunger. Open for inflow. When the pressure in the hydraulic chamber is high, the suction check valve closes, preventing fluid from flowing out of the hydraulic chamber, thereby preventing the chamber from shrinking and preventing the piston from retracting. Is prevented. As a result, a so-called "return function" is obtained.

The relief valve allows the tensioner to retract in response to a significant increase in chain tension. The relief valve typically has a check valve that is biased by a spring.
This check valve opens when the pressure in the hydraulic chamber becomes too high and exceeds a predetermined maximum level. The opening of the relief valve allows fluid to flow out of the pressure chamber, thereby reducing the hydraulic chamber and allowing the plunger to retract.

[0011] In operation, the tensioner spring and the working fluid move the piston outward to balance the inward force from the chain. As the tension in the chain increases, the chain exerts a force on the plunger in a plunger retracting direction. When the plunger is pushed in the retracted direction, the hydraulic pressure in the hydraulic chamber increases, at which time the suction check valve prevents fluid from flowing out of the hydraulic chamber. When the pressure in the hydraulic chamber exceeds a predetermined maximum level, the relief valve operates and opens,
Allow fluid to exit the hydraulic chamber.

If the chain tension decreases due to chain wear or other factors, and the pressing force of the chain against the plunger no longer balances the resultant force of the hydraulic pressure and the tensioner spring, the plunger protrudes toward the side of the chain. To apply tension to the chain. When the plunger protrudes toward the chain, the suction valve opens and hydraulic oil from an external oil source fills the hydraulic chamber.

[0013] The design of such hydraulic tensioners faces a number of problems. One problem is that air can be entrained in the oil in the hydraulic chamber. Because the air is compressible, any air in the hydraulic chamber will cause the plunger to retract slightly, reducing the pressing force supplied by the hydraulic pressure. As a result, the plunger cannot exert the intended tension on the chain.

The air in the hydraulic chamber is particularly problematic when starting the engine. After the engine stops, the air separates from the oil in the hydraulic chamber and rises to the highest position in the chamber. This results in a particularly sluggish tensioner and excessive noise when starting the engine.

One example of an apparatus designed to minimize the presence of air in a hydraulic chamber is described in US Pat. No. 4,708,696 to Kimura et al. Kimura et al. Employ various mechanisms to minimize air in the hydraulic chamber, including placing elastomeric elements and extendable accordion-like bellows in the hydraulic chamber. doing.

When the hydraulic chamber expands in response to the extension of the plunger, these devices expand to reduce the amount of flow increase required within the hydraulic chamber. This reduces the possibility of air entering the chamber.
However, these components cannot maintain their elasticity during prolonged use in the harsh environment of an internal combustion engine.

Other devices attempt to minimize air in the hydraulic chamber by providing a flow path for air to escape. U.S. Patent No. 5,314,388 by Suzuki et al.
Discloses a hydraulic tensioner with an air bleed mechanism. In this device, an air vent having a ball check valve is disposed on the top wall of the hydraulic chamber.

During operation of the engine, vibrations of the engine cause the air mixture fluid in the hydraulic chamber to vibrate. If air bubbles are present in the hydraulic chamber, such vibrations will cause air to pass through the check valve and out of the hydraulic chamber through the air vent. The disadvantages of this system are that not all of the air leaks out of the ball check valve, some of the working fluid is lost through the check valve, and air is externally passed through the check valve into the hydraulic chamber. The point is that there is even some inflow.

Similarly, other attempts have been made to provide a flow path for air within the hydraulic chamber to exit the hydraulic chamber. U.S. Pat. No. 4,826,470 to Breon et al. Discloses a hydraulic tensioner with at least one air vent so that when the tensioner rotates during operation, air escapes from within the chamber.

US Pat. No. 5,167,402 to Nakakubo et al. And US Pat. No. 5,366,415 to Church et al. Disclose hydraulic tensioners in which radial grooves leading to limited clearance are formed in the plunger wall. This allows air bubbles to pass through the groove and exit the hydraulic chamber from this clearance.

A disadvantage of these devices is that they include that the air does not follow the designated flow path to the outside of the chamber, so that the air may continue to interfere with the function of the tensioner. Moreover, many of these devices rely on engine vibration during operation to move air along the leak path. Therefore, these devices are not effective in preventing the presence of air in the hydraulic chamber at engine start.

A good tensioner design minimizes the possibility of air initially flowing into the hydraulic chamber. In the present invention, a structure that displaces fluid without interfering with the movement of the piston is located in the hydraulic chamber. The volume occupied by the structure reduces the volume of the high pressure chamber, thereby reducing the amount of air entering the high pressure chamber. The reduction in the air amount improves the performance of the tensioner at the time of starting and operating the engine.

The concept of reducing the volume of the high pressure chamber is used in other conventional tensioning devices. These devices use a solid plastic rod assembled into a piston tensioner spring. This rod is replaced by oil at the center of the spring.

These devices are difficult to assemble due to the risk that the rod will interfere with the tensioner spring. Furthermore, the piston housing of such a device is:
It must have an inlet for the source of pressurized fluid, an inlet check valve, a relief valve, an air vent, and means for securely securing the plastic rod to the housing. These requirements make the housing expensive to manufacture and difficult to assemble.

In contrast, the present invention includes a valve housing assembled within a piston tensioning spring. The valve housing has a hollow structure such as a cylinder, houses a suction valve and a relief valve, and acts as a fluid passage into and out of the hydraulic chamber. In one embodiment, an integrated suction and relief valve performs the functions of both the suction check valve and the relief valve.

The piston housing has an opening connected to an external source of pressurized fluid, and the valve housing has
It is sealed above this opening. Upon retraction or extension of the piston, fluid in the hydraulic chamber must pass through the valve housing into or out of the hydraulic chamber regulated by the suction and relief valve.

Advantages of the present invention include reducing the volume of the hydraulic chamber to minimize air entrainment into the hydraulic chamber. Also, by integrating the suction check valve, the relief valve and the suction portion inside the volume reduction structure, the present invention is easy to manufacture and assemble.

When the suction valve and the relief valve are
Integrating into the relief valve has the further advantage that the high pressure fluid exiting the fluid chamber through the relief valve is returned to an external source of pressurized fluid rather than inside the engine. As a result, the fluid is more effectively utilized.

Thus, an object of the present invention is to provide a hydraulic tensioner that can improve the response to changes in chain tension. It is another object of the present invention to provide a hydraulic tensioner that can minimize the amount of air in the hydraulic chamber, especially when starting the engine. Also,
It is yet another object of the present invention to provide a hydraulic tensioner having both suction check and pressure relief functions in a single housing. It is another object of the present invention to provide a hydraulic tensioner that can be easily manufactured and assembled.

[0030]

A hydraulic tensioner according to a first aspect of the present invention is a hydraulic tensioner for a power transmission device wound around a rotating member, the hydraulic tensioner being connected to a source of pressurized fluid. A housing having a bore and a housing bore, a hollow piston slidably received within the housing bore, a piston spring biasing the piston in a direction toward the power transmission, and a hollow including an inner chamber. A fluid having a valve housing having a structure and a plurality of valve housing openings, and an inner surface defined by the valve housing having an outer surface defined by an inner surface of the piston and an inner surface of the housing hole. A filled annular pressure chamber, wherein the valve housing flows between the inner chamber and the pressure chamber. Has a first valve housing opening connecting the inner chamber and the pressure chamber such that the second chamber has a second valve housing opening that can be connected to the first valve housing opening. The second valve housing aperture connects the inner chamber and the source of pressurized fluid such that fluid flows between the inner chamber of the valve housing and the source of pressurized fluid.

The hydraulic tensioner according to the second aspect of the present invention
2. The valve housing according to claim 1, wherein the valve housing has a hollow structure having an open end and a closed end.
It has a central longitudinal axis extending from the closed end to the open end, and has at least one valve housing opening through which fluid flows, and a plurality of valves are assembled in the hollow structure, and the valves are , Arranged to regulate the amount of fluid passing through the hollow structure.

The hydraulic tensioner according to the third aspect of the present invention
In claim 2, wherein the valve has an integrated suction and relief valve, wherein the suction and relief valve,
A pressurized fluid is arranged to move from the source of pressurized fluid to the pressure chamber, and the pressurized fluid is released from the pressure chamber only when the pressure of the fluid in the pressure chamber reaches a certain value. It is characterized by being arranged so as to allow movement of the fluid to the fluid source.

The hydraulic tensioner according to the invention of claim 4 is:
4. The first valve according to claim 3, wherein the suction / relief valve is a valve member that is movable in a vertical direction in the valve housing, a first valve seat, and a side that separates the valve member from the pressure chamber. A first valve spring biasing the valve seat side, a second valve seat, and a second biasing the first valve seat toward the second valve seat which is a side toward the pressure chamber. And a valve spring.

The hydraulic tensioner according to the invention of claim 5 is:
4. The first suction valve according to claim 3, wherein the suction / relief valve is a valve member that can move vertically in the valve housing, a first valve seat, and a side that separates the valve member from the pressure chamber. A first valve spring biasing toward a valve seat, a second valve seat, a holding member fixed in a vertical direction in the valve housing, and seated on the holding member;
A second valve spring for urging the first valve seat toward the second valve seat, which is a side toward the pressure chamber.

The hydraulic tensioner according to the invention of claim 6 is
In claim 5, the holding member is fixed to the valve housing by a corrugated portion in the valve housing.

The hydraulic tensioner according to the invention of claim 7 is:
3. The pressure chamber of claim 2, wherein the valve comprises a suction check valve, wherein the suction check valve is arranged to permit movement of pressurized fluid from the source of pressurized fluid to the pressure chamber, And is arranged to prevent movement of the pressurized fluid from the pressure fluid to the pressurized fluid source.

The hydraulic tensioner according to the invention of claim 8 comprises:
The suction check valve according to claim 7, wherein the suction check valve is vertically movable in the valve housing, a first valve seat vertically fixed to the valve housing, and And a first valve spring for urging the first valve member toward the first valve seat, which is a side away from the pressure chamber.

The hydraulic tensioner according to the ninth aspect of the present invention
The first valve seat according to claim 4, wherein the first valve seat is formed to seal against the valve member, and the first valve seat is formed to seal against the second valve seat. And two sealing surfaces.

According to a tenth aspect of the present invention, in the hydraulic tensioner according to the first aspect, the piston has a cylindrical shape, the first valve seat is formed in an annular shape, and the width of the valve member is increased. The second valve seat has an outer diameter portion larger than the inner diameter of the second valve seat.

According to an eleventh aspect of the present invention, in the hydraulic tensioner according to the first aspect, the piston has a closed end, and a flow path at the closed end extends from an inner surface of the piston to an outer surface of the piston. , Wherein the flow path functions as an air vent.

In the hydraulic tensioner according to the present invention,
A hollow valve housing is provided in the housing. The volume occupied by the valve housing reduces the substantial volume of the pressure chamber, thereby minimizing the possibility of air initially entering the pressure chamber. As a result, the amount of air existing in the pressure chamber can be minimized, and the response performance of the tensioner at the time of starting and operating the engine can be improved.

Further, according to the present invention, since the valve assembled inside the valve housing is integrated,
The manufacture and assembly of the hydraulic tensioner can be facilitated.

[0043]

DETAILED DESCRIPTION OF THE INVENTION According to one aspect of the Summary of the Invention The invention, tensioner for wound around the power transmission device, for example a chain connecting at least two rotating members such as a pair of sprockets is provided ing. A piston is slidably provided in the bore of the piston housing and defines a hydraulic chamber. A spring that biases the piston outward from the bore is contained within the hydraulic chamber.

The present invention relates to the design of a tensioner to minimize the amount of air present in the hydraulic chamber. The hydraulic chamber is filled with a pressurized fluid and has an outlet at the end of the bore that leads to an external source of pressurized fluid.

A valve housing is arranged inside the piston spring. The valve housing has a hollow structure and is located in a portion of the piston housing that surrounds an outlet communicating with an external pressurized fluid. The volume occupied by the valve housing has the effect of displacing the fluid in the hydraulic chamber, thereby reducing the substantial volume of the hydraulic chamber. This reduced volume minimizes the amount of air present in the hydraulic chamber, thereby improving the performance of the tensioner.

A valve for adjusting a flow rate flowing into the hydraulic chamber and a flow rate flowing out of the hydraulic chamber is assembled in the valve housing. Preferably, an integrated suction and relief valve is employed.
This valve only allows fluid to flow into the hydraulic chamber and allows fluid to flow out of the hydraulic chamber when the hydraulic pressure in the hydraulic chamber reaches a certain limit. It is. Such flow regulation provides a tensioner that is sensitive to changes in chain tension, and the use of a single valve housing provides manufacturing and assembly advantages.

For a better understanding of these and other features and objects of the present invention, reference should be had to the following detailed description, taken in conjunction with the accompanying drawings.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. The present invention seeks to provide a hydraulic tensioner that utilizes the reduced volume of a hydraulic chamber. This tensioner has a large volume structure in a hydraulic chamber, which acts as a flow path for pressurized fluid and houses a valve that regulates the flow into and out of the hydraulic chamber. doing. Reducing the volume increases the responsiveness of the tensioner, and using the valve housing to reduce the volume facilitates manufacture and assembly.

FIG. 1 shows an embodiment of the present invention.
The power transmission device 10 has a chain 12 operated between two sprockets 14 and 16. The lever arm 18 attached to the pivot shaft 20 exerts a pressing force on the chain 12 to exert a tension. The hydraulic tensioner 100 has a plunger 110 for applying a pressing force to the lever arm 18.

FIG. 2 is a side view of one embodiment of the present invention. The tensioner 100 has a piston housing 102. The piston housing 102 has a cylindrical hole 1
04 and an inner peripheral surface 106 of the hole 104. The piston housing 102 has an opening 108 at the closed end 110 of the hole 104. The opening 108 is connected to a reservoir (not shown) or an external pressurized fluid source.

The cylindrical piston 130 has the piston hole 1
04 is slidably assembled. The piston 130 has a cylindrical body 132 with a closed end 134.
have. In some embodiments, the closed end 134 is provided with a vent 160 that evacuates air and some fluid from within the piston housing 102.

In some embodiments, the piston 1
A seal ring 136 is housed in a groove 138 formed on the outer peripheral surface 139 of the device 30. This seal ring 1
36 seals between the outer peripheral surface 139 of the piston and the inner peripheral surface 106 of the piston hole 104. In another embodiment, the seal ring is provided on the inner peripheral surface 10 of the piston bore 104.
6.

Assembled concentrically with the piston 130 is a piston spring 170. The piston spring 170 urges the piston 130 outward from the piston housing 102 so that the piston tip 131 presses the lever arm 18 shown in FIG.

Assembled within piston spring 170 is valve housing 200. This is a structure whose volume replaces most of the fluid inside the piston spring.

In one embodiment, the valve housing 200 is substantially cylindrical and has an inner chamber 313 therein. The shape of the valve housing 200 is not limited to a cylindrical shape, and other shapes can be adopted. In a preferred embodiment, for example, as shown in FIGS. 5, 6, 8 and 9, the valve housing has two cylindrical body portions 610, 620 having different radii and these body portions Are separated by a shoulder 615. In a preferred embodiment, the valve housing has both a suction check valve and a relief valve.

The valve housing 200 has a closed end 210.
And an approximately cylindrical shape having an open end 212. In some embodiments, as shown in FIGS. 3 and 4, the closed end 210 has an aperture 216 through which fluid flows. In the preferred embodiment shown in FIGS. 5 and 6, a plurality of apertures 216 are provided in the cylindrical body portion 610 substantially adjacent the closed end 210.
The open end 212 is sealed with respect to the closed end 110 of the piston hole 104.

In one embodiment, the seal plug 15
0 is provided between the open end 212 of the valve housing 200 and the closed end 110 of the piston hole 104, and seals between these surfaces. In a preferred embodiment, the open end 212 of the valve housing 200 has a radially extending flange 214. This flange 2
14 is seated on the seal plug 150 and also on the piston spring 170.

Thus, the high-pressure fluid chamber 180
Are formed in the piston housing 102. The high-pressure fluid chamber 180 is formed in an annular shape, and its outer peripheral surface is formed by the inner peripheral surface 137 of the piston 130 and the inner peripheral surface 106 of the piston housing hole 104. Seal ring 136 prevents fluid from leaking from high pressure fluid chamber 180 through the gap between piston 130 and piston housing 102. The top of high pressure fluid chamber 180 is formed by closed end 134 of piston 130.

The inner peripheral surface of the high-pressure fluid chamber 180 is formed by the outer peripheral surface 139 of the piston 130. The bottom of the high-pressure fluid chamber 180 is formed by a seal plug 150.

Assembled inside the valve housing 200 is a valve that regulates the flow of fluid into and out of the high pressure fluid chamber 180. In the preferred embodiment, an integrated suction and relief valve 300 is employed. The valve includes a suction check valve that allows the flow of pressurized fluid into the high pressure fluid chamber and prevents the fluid from flowing out of the high pressure fluid chamber, and increases the pressure when the fluid pressure reaches a certain level. It has a dual function with a relief valve that allows fluid to flow out of the high pressure fluid chamber only to open.

The valve has another feature that the fluid passing through the relief valve is discharged to an external fluid source, so that the fluid can be efficiently reused. ing.

The integrated suction / relief valve 300 is
It is composed of many elements. A spring retainer washer 310 is incorporated in the valve housing 200 so that its axial position with respect to the valve housing 200 is fixed.

On the spring retainer washer 310, a pressure relief spring 312 is provided concentrically with the valve housing 200. An annular pressure relief disk 314 is provided concentrically within the valve housing 200 at the end of the pressure relief spring 312 on the opposite side of the spring retainer washer 310.

As described above, the pressure relief spring 312 is supported by the fixed spring retainer washer 310 and the pressure relief disk 314 is moved to the closed end 2 of the valve housing 200.
It is biased to the 10 side.

When the pressure in the high-pressure fluid chamber exceeds a predetermined maximum value, as shown by the arrow in FIG.
14 releases pressure away from the closed end 210 of the valve housing 200. Pressure relief disc 31
4 has an outer diameter part 315 and an inner diameter part 316.

The pressure relief disk 314 is seated on the pressure relief seat 318 by being urged toward the closed end 210 side of the valve housing 200.

In one embodiment, as shown in FIG. 2 and FIG.
Is a cylindrical member supported by the closed end 210 of the valve housing 200, and has an inner diameter portion 319 smaller than the outer diameter portion 315 of the pressure relief disk 314.

In a preferred embodiment, as shown in FIGS. 5 and 6, the pressure relief sheet 318
Is an annular member fixed to the shoulder 615 of the valve housing 200. The pressure relief sheet 3
Reference numeral 18 may be any member fixed to the valve housing 200 and capable of forming a sealing surface with the pressure relief disk 314.

The valve member 330 is also seated on the pressure relief disk 314. In one embodiment, the valve member 330 is a ball having a diameter greater than the inner diameter 316 of the pressure relief disk 314 and less than the inner diameter 319 of the pressure relief seat 318. In this case, the valve member 3
30 can move freely in the axial direction with respect to the pressure relief sheet 318, but cannot pass through the inner diameter of the pressure relief disk 314 because of its size.

Although the valve member 330 is preferably a ball, it can take a variety of geometric shapes. For example, the valve member 330 is a disc or a tapered plug (not shown). If a tapered plug is used, the small end is located near pressure relief disc 314 and the large end is suction check spring 332.
Is arranged in the vicinity of.

The exact shape is, of course, determined by the required dynamic response. For example, a solid ball has a large mass, and therefore has a slow response time and a low natural frequency compared to a small and lightweight disk or a hollow metal ball. The valve member may also be comprised of an engineering plastic such as polyimide or a ceramic.

The valve member 330 is connected to the closed end 2 of the valve housing 200 by the suction check spring 332.
It is urged away from 10. One end of the spring 332 contacts the closed end 210 of the valve housing 200, and the other end contacts the valve member 330. Thus, the suction check spring 332 urges the valve member 330 toward the pressure relief disk 314. When the pressure in the high pressure fluid chamber falls below a predetermined minimum value due to the outward movement of the plunger, the suction check valve opens and fluid flows into the high pressure fluid chamber, as indicated by the arrow in FIG.

As described above, the valve functioning as both the suction check valve and the relief valve is formed in the valve housing 200. Valve member 33
0 is the inner diameter 3 of the pressure relief disk 314
The first seal portion 331 is formed. In addition, the pressure relief disk 314 is urged toward the pressure relief sheet 318 side, so that the second seal portion 317
Are formed.

Under static conditions, these two seals cooperate to prevent fluid from escaping from the valve housing 200, thereby providing a high pressure fluid chamber 1
80 is sealed from an external source of pressurized fluid.

The suction check function is performed by the first seal portion 33.
1 is performed. Under typical conditions, the first seal 3
31 prevents any fluid from flowing into the high pressure fluid chamber 180. However, if the pressure in the high pressure fluid chamber 180 is lower than the pressure of the external source of pressurized fluid, the force to open the valve member 330 in the direction toward the valve housing closed end 210 will be applied to the valve member 33.
Acts on zero. This force is applied to the suction check spring 33
2 is dragged.

If the pressure in the high pressure fluid chamber becomes sufficiently low, the valve member 330 moves away from the pressure relief disk 314 and opens the first seal portion 331. Then, the fluid from the external source of pressurized fluid, as indicated by the arrow in FIG.
Flows into the high-pressure fluid chamber 180 through the periphery of the valve member 330 from the inner diameter portion 316. At this time, the spring force of the suction check spring 332 is balanced with the force required to allow fluid to flow into the high-pressure fluid chamber 180 from an external fluid source.

The pressure relief function is performed by the pressure relief disk 314 and the pressure relief sheet 3.
This is performed at the second seal portion 317 between the intervals 18. Under typical conditions, this seal is in the high pressure fluid chamber 1
Prevents fluid from flowing out of 80. The hydraulic pressure acting on the outside of the pressure relief disk 314, the valve member 330, and the inside of the pressure relief disk 314 from the valve member 330 causes the pressure relief disk 314 to open toward the side away from the pressure relief sheet 318. This force is received by the urging force of the pressure relief spring 312.

If the pressure in the high pressure fluid chamber becomes too high, the pressure relief disk 314 separates from the pressure relief sheet 318 and opens the second seal 317. Then, the fluid in the high-pressure fluid chamber 180 flows from the opening 216 of the valve housing closed end 210 to the outer diameter portion 315 of the pressure relief disk 314 and the inner diameter portion 319 of the pressure relief sheet 318 as shown by the arrow in FIG. Through the gap to an external source of pressurized fluid. At this time, the spring force of the pressure relief spring 312 is balanced in the high-pressure fluid chamber with the force required to allow the fluid to flow out of the chamber.

The suction check spring 332 and the pressure relief spring 312 are made of any steel usually used for such an application. The suction check spring is typically designed for a cracking pressure of a few PSI. On the other hand, pressure relief springs are typically set at a much higher cracking pressure of about 250 PSI.

This pressure relief valve also has
Has a unique assembly method. First, the pressure relief seat 318, the suction check spring 332, the valve member 330, and the pressure relief disk 3
14 is inserted into the valve housing 200. next,
The pressure relief spring 312 is inserted.
Then, the spring retainer washer 310 is inserted and placed in the valve housing 200 according to the desired final spring force. This final spring force is determined by the desired cracking pressure of the pressure relief valve.

Next, the spring retainer washer 31
0 is fixed to the valve housing 200 by providing a wave portion on the valve housing 200 at the upper and lower portions of the washer.

This method reduces the change in the cracking pressure of the pressure relief valve by reducing the accumulation of tolerances. The method also allows for different cracking pressures with the use of the same spring by adjusting the final load of the spring retainer washer 310.

In operation, high pressure fluid chamber 180 is filled with pressurized fluid. If the power transmission chain becomes loose, the piston spring 170 causes the piston 130 to protrude. FIG. 3 or FIG. 9 shows a preferred embodiment of the present invention with the piston 130 protruding.

As piston 130 protrudes, the pressure in high pressure fluid chamber 180 decreases. When the pressure in the high pressure fluid chamber 180 drops to a certain value, the suction check valve opens and fluid from an external source of pressurized fluid flows into the high pressure fluid chamber 180 (see FIG. 5).

As the tension of the chain 12 increases, the chain 12 exerts a pressing force on the piston 130 via the lever arm 18. The pushing force from the chain 12 increases the pressure in the high pressure fluid chamber because the suction check valve does not allow fluid to flow out of the high pressure fluid chamber. When the pressure in the chamber exceeds a certain value, the pressure relief valve opens and fluid flows out of the high pressure fluid chamber through the valve housing 200 (see FIG. 6).

The escaping fluid returns to the source of pressurized fluid through the piston housing aperture 108 so that fluid in the system is not lost. The outflow of the fluid causes the piston 130 to retract. FIG. 2 or FIG.
30 shows a preferred embodiment of the present invention in the state where 30 is in a degenerated state.

Under any conditions, the design of the tensioner requires that the presence of air in the high pressure fluid chamber be minimized. When the tensioner draws fluid from an external fluid source, the fluid contains some entrained air. Because air is compressible, entrained air in the chamber causes the high pressure fluid chamber to contract even when no fluid is flowing out of the chamber. As a result, the tensioner does not exert a sufficient pressing force on the lever arm 18, and generally the response to the change in the chain tension is deteriorated.

After the engine stops, the air in the chamber separates from the fluid and rises to the highest position in the high-pressure fluid chamber. This results in a particularly responsive chain when the engine is started. That is, more efficient tensioners contain minimal air in the high pressure fluid chamber.

In the present invention, the volume occupied by the valve housing 200 replaces the fluid in the high pressure fluid chamber, thereby reducing the total volume of the high pressure fluid chamber. Reducing the volume of fluid in the high pressure fluid chamber necessarily reduces the amount of air in the high pressure fluid chamber, as air is carried within the fluid. As a result, the performance of the tensioner is improved.

FIGS. 4 and 7 each have a valve housing for reducing the volume.
Figure 3 shows an embodiment of the invention with only a suction check valve, not a relief valve.

In the embodiment shown in FIG. 4, the basic design is the same as in FIGS. 2 and 3, except that no pressure relief valve is present.
In this case, the suction check sheet 530 has a cylindrical main body 534 and a flange 536 extending radially inward near the valve member 532. Flange 536 includes a valve member 53, preferably a ball.
2 has an inner diameter smaller than the outer diameter.

A suction check spring 538 urges the valve member 532 toward the flange 536 to form a seal. The seal opens when the hydraulic pressure on the ball reaches a certain level due to the pressure difference between the external fluid source and the high pressure fluid chamber.

In the embodiment shown in FIG. 7, the basic design is similar to the embodiment shown in FIGS. 5 and 6, except that no pressure relief valve is present. A suction check sheet 580 is fixed in the valve housing 200 in the axial direction. The check sheet 580 is installed, for example, by checking the check sheet 580.
To the shoulder 589 and / or corrugations 588 of the valve housing 200. Check seat 580 has an inner diameter 586 that is smaller than the diameter of valve member 582, which is preferably a ball.

A suction check spring 590 urges the valve member 582 toward the check seat 580 to form a seal. The seal opens when the hydraulic pressure on the valve member reaches a certain level due to the pressure difference between the external fluid source and the high pressure fluid chamber.

Those skilled in the art to which the present invention pertains will appreciate, in light of the above teachings, various modifications which may employ the principles of the present invention without departing from the spirit or essential characteristics thereof. And other embodiments may be constructed. The above-described embodiments are to be considered in all respects only as illustrative and not restrictive.

Therefore, the scope of the invention is indicated by the appended claims rather than by the foregoing description. Thus, while the invention has been described in relation to particular embodiments, changes in structure, sequence, material and other modifications will be apparent to those skilled in the art, while remaining within the scope of the invention.

[0097]

As described above in detail, according to the hydraulic tensioner of the present invention, since the valve housing is provided in the housing, the substantial volume of the pressure chamber is reduced by the volume occupied by the valve housing. Can be reduced. Thereby, the amount of air existing in the pressure chamber can be minimized, and as a result, the response of the tensioner can be improved.

[Brief description of the drawings]

FIG. 1 is a side view of a power transmission operated with a hydraulic tensioner according to one embodiment of the present invention.

FIG. 2 is a side sectional view showing a state in which a plunger is retracted in the hydraulic tensioner according to one embodiment of the present invention.

FIG. 3 is a side sectional view showing a state in which a plunger is extended in a hydraulic tensioner according to an embodiment of the present invention.

FIG. 4 is a side sectional view of a hydraulic tensioner according to another embodiment of the present invention.

FIG. 5 is a side sectional view of a hydraulic tensioner according to still another embodiment of the present invention, showing a state where an intake check portion of an integrated intake / relief valve is opened.

FIG. 6 is a side sectional view of a hydraulic tensioner according to still another embodiment of the present invention, showing a state in which a relief portion of an integrated suction / relief valve is opened.

FIG. 7 is a side sectional view of a hydraulic tensioner according to another embodiment of the present invention.

FIG. 8 is a view showing a state in which a plunger is retracted in a hydraulic tensioner (FIGS. 5 and 6) according to still another embodiment of the present invention.

FIG. 9 is a view showing a state where a plunger is extended in a hydraulic tensioner (FIGS. 5 and 6) according to still another embodiment of the present invention.

[Explanation of symbols]

Reference Signs List 10 power transmission device 12 chain 14, 16 sprocket (rotating member) 100 hydraulic tensioner 102 housing 104 hole 130 (hollow) piston 170 piston spring 180 (pressure) chamber 200 valve housing 213 corrugated portion 216 first valve housing opening 300 Suction relief valve 310 Spring retainer washer (holding member) 311 Second valve housing opening 312 Pressure relief spring (second valve spring) 313 Inner chamber 314 Pressure relief disk (first valve seat) 317 Second seal portion 318 Pressure relief seat (second valve seat) 330 Valve member 331 First seal portion 332 Suction check spring (First valve spring) ) 530 suction check sheet (first valve seat) 532 Valve member 538 inlet check spring (first valve spring

Claims (11)

[Claims] 1. A hydraulic tensioner for a power transmission device wound between rotating members, comprising: a housing having an opening communicating with a source of pressurized fluid and having a housing hole; A hollow piston slidably received on the piston, a piston spring biasing the piston in a direction toward the power transmission device, a valve housing having a hollow structure including an inner chamber, and having a plurality of valve housing openings. An annular pressure chamber having an inner surface defined by the inner surface of the piston and an inner surface of the housing bore, an inner surface defined by the valve housing, and being filled with a fluid; Fluid flows between the inner chamber of the valve housing and the pressure chamber. A first valve housing opening connecting the inner chamber and the pressure chamber, wherein the valve housing has a second valve housing opening that can be connected to the first valve housing opening. Wherein the second valve housing opening connects the inner chamber and the source of pressurized fluid such that fluid flows between the inner chamber of the valve housing and the source of pressurized fluid. Hydraulic tensioner. 2. The hydraulic tensioner according to claim 1, wherein the valve housing has a hollow structure having an open end and a closed end, and the hollow structure extends in a longitudinal direction from the closed end to the open end. A central axis and having at least one valve housing aperture through which fluid flows, wherein a plurality of valves are assembled within the hollow structure, and the valves regulate the amount of fluid passing through the hollow structure; The hydraulic tensioner is arranged as follows. 3. The hydraulic tensioner according to claim 2, wherein said valve comprises an integral suction and relief valve, said suction and relief valve delivering pressurized fluid from said pressurized fluid source to said pressure. To move the fluid from the pressure chamber to the source of pressurized fluid only when the pressure of the fluid in the pressure chamber reaches a certain value. A hydraulic tensioner, which is disposed. 4. The hydraulic tensioner according to claim 3, wherein the suction / relief valve comprises: a valve member movable vertically in the valve housing; a first valve seat; A first valve spring that urges the first valve seat away from the chamber, a second valve seat, and the second valve seat that faces the first valve seat toward the pressure chamber. A second valve spring biasing the valve seat side. 5. The hydraulic tensioner according to claim 3, wherein the suction / relief valve comprises: a valve member movable vertically in the valve housing; a first valve seat; A first valve spring that urges the first valve seat, which is a side away from the chamber, a second valve seat, a holding member fixed in a vertical direction in the valve housing, and the holding member. A second valve spring that is seated and urges the first valve seat toward the second valve seat that is the side toward the pressure chamber. Tensioner. 6. The hydraulic tensioner according to claim 5, wherein the holding member is fixed to the valve housing by a corrugated portion in the valve housing. 7. The hydraulic tensioner of claim 2, wherein the valve comprises a suction check valve, wherein the suction check valve allows movement of pressurized fluid from the source of pressurized fluid to the pressure chamber. And a fluid tensioner arranged to prevent movement of pressurized fluid from the pressure chamber to the source of pressurized fluid. 8. The hydraulic tensioner according to claim 7, wherein the suction check valve is fixed to a first valve member movable vertically in the valve housing, and is fixed to the valve housing in a vertical direction. First
And a first valve spring that biases the first valve member toward the first valve seat that is away from the pressure chamber. Pressure tensioner. 9. The hydraulic tensioner according to claim 4, wherein the first valve seat has a first sealing surface formed so as to seal against the valve member, and the second valve seat has a second sealing surface.
A second sealing surface formed so as to seal against the valve seat of (1). 10. The hydraulic tensioner according to claim 1, wherein the piston has a cylindrical shape, and the first valve seat is formed in an annular shape, and has an inner diameter smaller than a width of the valve member. A hydraulic tensioner having an outer diameter portion larger than the inner diameter of the second valve seat. 11. The hydraulic tensioner according to claim 1, wherein the piston has a closed end, a flow path at the closed end extends from an inner surface of the piston to an outer surface of the piston, and the flow path has a closed end. A hydraulic tensioner that acts as an air vent.